Imagine on your daily commute to work you decided to drive a little faster, and by doing so slightly increased your risk of getting into a wreck.
When a wreck does happen, what is the primary cause? Is it the speed, the wet roads, the fact you were sending a text?
The primary cause may not have been the speed itself, but it was part of the equation.
That’s how climate scientists described their work during a news conference Sept. 5 on studies that try to tease out what parts of extreme weather could be attributed to climate change.
The news conference coincided with a report issued on 12 extreme weather events in 2012 that scientists studied to determine if human-influenced climate change played a part.
The scientists found that such climate change was indeed a factor in about half of those events.
All of them would have happened with, or without, climate change being a factor, said Thomas Karl, director of the National Oceanic and Atmospheric Association’s National Climatic Data Center.
The question is: What part did human-related climate change play?
The extreme weather events that were studied weren’t selected because they were the “most extreme” of the year; rather, they were chosen because they were in areas where scientists lived or were working, said Peter Scott, climate scientist with the United Kingdom Met Office.
One study found that human-related climate change had very little impact on the lack of rain in the central United States.
Another study examined heat waves in the U.S. during the spring and summer, and found that although they could be explained mainly by natural processes, human-related climate change was involved in how warm it got and the likelihood that similar heat waves would happen again.
“High temperatures, such as those experienced in the U.S. in 2012, are now likely to occur four times as frequently due to human-induced climate change,” according to a news release about the report. “Approximately 35 percent of the extreme warmth experienced in the eastern U.S. between March and May 2012 can be attributed to human-induced climate change.”
A third study examined Hurricane Sandy, which caused widespread destruction along the East Coast, and found that the destruction was largely caused by the storm surge that flooded coastal areas.
“However, climate-change-related increases in sea level have nearly doubled today’s annual probability of a Sandy-level flood recurrence as compared to 1950,” according to the release.
The report was released by the Bulletin of the American Meteorological Society. It is the work of 18 research teams from various countries that examined extreme weather events on five continents and the Arctic.
The report — called “Explaining Extreme Events of 2012 from a Climate Perspective” — was peer-reviewed, and three of its four lead editors are from NOAA.
The research represents a slight change in direction.
Climate change scientists used to focus on large phenomena such as global temperatures, said Thomas Peterson, principal scientist with NOAA’s National Climatic Data Center. Through that work, there developed a mantra that you can’t attribute any one thing to climate change.
By the time that mantra made it into the political realm, the science had moved on.
Now it is possible to tease from smaller weather events any effects of human contributions to climate change.
Amy Wold covers environmental issues for The Advocate. Follow her on Twitter at @awold10 or contact her at awold@ theadvocate.com.